- LNU is pretty simple an extension, and not dangerous at all, as far as I know. However, be sure to backup your profile before using a nightly build for they often are on the bleeding edge, meaning that the blood on the edge may well end up being yours. As they say on the Calendar Project web site: "Please be aware, that the use of nightly developer builds has risks associated with it. Don't use them with production data, as data loss and other scary things can occur. We're not kidding". Well that was scary indeed =)